As is known, rear lights of automobiles are usually made up of: a rigid rear body, which is substantially basin-shaped and is structured in so as to be stably recessed within a compartment specifically provided in the rear part of the vehicle body; a front lenticular half-shell, which is at least partially made of transparent or semitransparent plastic material, usually also coloured, and is arranged to close the mouth of the rear body so as to surface on the outside of the vehicle body; one or more incandescence light bulbs, each of which is located close to the bottom of the rear body more or less aligned with a corresponding transparent or semitransparent portion of the front lenticular half-shell so to be able to backlight the same transparent or semitransparent portion the half-shell; and one or more reflecting bodies having a roughly parabolic profile and being each fitted on a corresponding incandescence light bulb so as to be able to direct all the light produced by the light bulb towards the superjacent transparent or semitransparent portion of the front lenticular half-shell.
In some models of automotive rear light, moreover, the front lenticular half-shell is also provided with a long transparent or semitransparent ribbon-like portion, which usually extends parallel to the ground; and the automotive light is provided with a row of incandescence light bulbs which are aligned one side by side the other underneath the entire transparent or semitransparent ribbon-like portion so that each of them is able to backlight a respective sector of the transparent or semitransparent ribbon-like portion.
Light bulbs located underneath the transparent or semitransparent ribbon-like portion are usually turned on in sequence so as to create, on the front lenticular half-shell, a small luminous area/zone that displaces/moves along the front lenticular half-shell in a direction parallel to the ground. This mobile light signal is generally used as turning indicator of the vehicle.
In the course of the last few years, some manufacturers of automotive lights decided to replace the row of incandescence light bulbs with a long row of light-emitting diodes (LEDs) located immediately underneath the transparent or semitransparent ribbon-like portion, throughout the length of the ribbon-like portion.
Unfortunately, LEDs are point-type light sources thus a large number of LEDs is necessary to be able to backlight adequately the entire transparent or semitransparent ribbon-like portion of the front lenticular half-shell. The distribution of the LEDs, in fact, must be such as to produce a particularly intense light signal which is capable to match the photometric specifications envisaged for type-approval of motor vehicles direction lights, and which moreover has a light intensity as uniform as possible throughout the length of the transparent or semitransparent ribbon-like portion of the half-shell, thus to meet the aesthetic requirements of manufacturers of automobiles, motor cycles, and the like.
Obviously, the large number of LEDs required has caused a significant rise in the overall production costs of automotive lights, with all the problems that this entails.